1. Field of the Invention
The present invention relates to an image forming apparatus for forming an image according to image information sent from an external apparatus such as a printer, and in particular to an image forming apparatus which is required to inform a user of replacement or supply of a consumable (developer) under a network environment, a control method for the image forming apparatus, a developing apparatus for the image forming apparatus, and a memory medium mounted on the developing apparatus.
2. Related Background Art
A method of forming a color image in an image forming apparatus as shown in FIG. 15 will be described. First, latent images, which are formed on a photosensitive drum 2 according to image information sent for each color in an optical unit 9, are developed and visualized with developers held in respective color developing apparatuses 151Y, 151M, 151C and 151K provided in a developing apparatus selection mechanism part 150. The visualized images are transferred onto an endless image bearing member 5 a plurality of times, and a multi-color image is formed on the endless image bearing member 5. Thereafter, a transfer material P selected in and fed from transfer material holding members (hereinafter referred to as sheet feed trays) 12 to 16 is conveyed to the part between the endless image bearing member 5 and a transfer/conveyor belt 6, and the multi-color image on the endless image bearing member 5 is transferred onto the transfer material P. The multi-color image transferred onto the transfer material P is thermally fixed on the transfer material P by a fixing unit 7. Thereafter, the transfer material P is conveyed and discharged to an upper tray part 19 or a lower sheet discharge tray part 20. Note that, in the case of monochrome image formation, an image developer of a single color is used to form a multiple image.
Next, a method of detecting a residual amount of developer will be described in detail.
There have been disclosed several methods of detecting a residual amount of developer to the present.
For example, there are known a method of detecting an electrostatic capacitance held by a developer in a developing apparatus to use the electrostatic capacitance for detection of a residual amount, which has already been generally used (e.g., Japanese Patent Application Laid-Open No. 5-6092), a method of detecting reflected light or transmitted light using an LED of infrared ray and an optical sensor for photoreception to use the reflected light or the transmitted light for detection of a residual amount of developer according to intensity of the detected photoreceptive intensity (e.g., Japanese Patent Application Laid-Open No. 7-140776), and a method of presuming a consumption amount of developer based upon image information at the time of image formation to use the consumption amount for detection of a residual amount (e.g., Japanese Patent Application Laid-Open No. 2001-318566).
In addition, a method of detecting a residual amount of developer using an optical system requires an optical path without a developer, through which light passes, in order to detect a residual amount of developer. That is, since light is not transmitted until the developer is used and the residual amount of developer reaches a level of a certain degree, it is difficult to detect a change in the residual amount. Thus, it is extremely difficult to sequentially detect a change in the residual amount of developer from the time when the developer is filled to a maximum degree until the time when the developer is fully consumed. In addition, contrary to the above-described method, a method of detecting a residual amount of developer of an antenna system for detecting an electrostatic capacitance in a developing apparatus can measure, with extremely high accuracy, an amount of electrostatic change from the time when a developer is filled to a maximum degree until the time when the developer has been reduced to a fixed amount. However, if the developer has been reduced to less than the fixed amount, an electrostatic capacitance is reduced to an extremely small amount. Thus, it is difficult to sequentially detect a change in the electrostatic capacitance at the time when the residual amount of developer is small. There has also been proposed to use both the above-described methods to compensate for the respective disadvantages (e.g., Japanese Patent Application Laid-Open No. 2001-228698). However, for example, in an image forming apparatus having a developing apparatus holding member of a portable type rather than a fixed developing apparatus, since an electrostatic capacitance in the developing apparatus changes largely in accordance with movement of the developing apparatus, the above-described effect cannot be obtained sufficiently in some cases.
However, with the method of presuming a consumption amount of developer based upon image information at the time of image formation to use the consumption amount for detection of residual amount, it is difficult to perform optimum presumption of a consumption amount of developer in the case in which consumption efficiency of the developer is different largely between an initial state of an image forming unit and a state after endurance due to image formation of the image forming unit.
In addition, in the developing apparatus, consumption efficiency of a developer, deterioration of electric characteristics of the developer in the developing apparatus, and abrasion of a developer regulating member or the like are different between the initial state of the image forming unit and the state after endurance due to image formation of the image forming unit. Thus, it is likely that deterioration of quality of an image, a trouble such as leakage of the developer, or the like is caused. Therefore, in order to prevent the above-described troubles from occurring, in a multi-color image forming apparatus, it is becoming necessary to detect a life of a developing apparatus taking into account not only a residual amount of developer but also deterioration of the developer and deterioration of a developer carrying member.